Trying to figure out what's letting-go in the front-end - Chevy Impala SS Forum
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post #1 of 18 (permalink) Old 03-15-2017, 08:00 AM Thread Starter
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Trying to figure out what's letting-go in the front-end

When I apply the brakes, hard, there's a slight clunk from the driver's front tire. I've gotten under there and poked and prodded and everything looks ok, but something is obviously wrong. The car will also find a groove in the pavement and pull to that side pretty hard - then clear up. Increased tire wear up front is also noticed.

So the short of it, how do I figure out what part up there is going bad? Use a prybar and start trying to move things like balljoints, tie-rod ends, etc? Get it in the air and try to move things by hand?

Thanks for your assistance. Front-end work is not my thing.


1995 Caprice ERE 383, CIA long tubes, Dynomax VT's, RAISS, Kore3/Z06 brakes, 3.42 posi, Boss 338 20's, 12 way seats, Impala SS console, etc etc etc
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post #2 of 18 (permalink) Old 03-15-2017, 08:50 AM
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I vote failing upper control arm bushing(s) or missing alignment shims, which will result in the UCA moving--ball joint/top of spindle will move forward under braking, which can cause the "clunk"....in normal driving, a bad bushing or missing shim will let the UCA float (pivot forward & aft) by influences like a rut, as you describe.

As the top of the spindle moves, even a very small amount, it will affect the alignment, and will change toe setting, assuming the steering linkage is to specs.

Shims fall out when an alignment is done and the locking nuts aren't replaced, and end up loosening over time--the self-locking design was only meant to last for a couple of alignments, but we're dealing with 20+ year-old vehicles....many which have NEVER had these nuts replaced.
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post #3 of 18 (permalink) Old 03-15-2017, 01:44 PM
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Hint: Noise locations are misleading from the driver's seat. Honestly your symptoms could be as simple as a loose battery or rotted rad support, coupled with terrible alignment. A little further stretch to what Bill listed may be well overdo Idler Arm, or center link. As you proposed, have someone cycle the wheel while you're under it. Of course eagle eye any place you (or especially anyone else) did any recent work.

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post #4 of 18 (permalink) Old 03-15-2017, 01:58 PM
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I had a similar experience with my 9C1. I rebuilt the OEM control arms with Del-A-Lum bushings. Not long after the install, I would hear/feel a clunk when braking.

I ended up taking a good look at the bushing 'ear' of the lower control arms, and saw that the hole in the original arm was worn out, and the control arm was sliding on the bushing housing.

Take a careful look at the front suspension components and see if you can find any fresh scrape marks.

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post #5 of 18 (permalink) Old 03-16-2017, 09:43 PM
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You did not state what the tire wear pattern is. It would help find a more specific issue.


I vote with Navy Lifer. You are too far south to have a lot of rust issues, unless it is a rustbelt car. I had the same symptoms, and it was the upper front control arm bushing. If you are going to replace bushings, You might as well replace the BJs, and you can get the whole arm from Rock Auto as cheap as the parts. You just bolt it on, and get an alignment. If you tap the mounting studs out, the arms are a lot easier to install. Use a regular nut to draw the studs back into the shaft and frame. Keep your shim stacks together for an alignment starting point. Get the MOOG parts/arms.

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post #6 of 18 (permalink) Old 03-20-2017, 12:10 PM Thread Starter
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Quote:
Originally Posted by Fred Kiehl View Post
You did not state what the tire wear pattern is. It would help find a more specific issue.
Drivers-side inner wear. After getting under it this weekend and pushing / pulling on everything - a close inspection showed space between the bushing and the metal-cup on the outside of the upper control arm. It was either never tightened to spec, or the bushing has degraded over time and allowed slop into the mix.

Quote:
Originally Posted by Fred Kiehl View Post
If you tap the mounting studs out, the arms are a lot easier to install. Use a regular nut to draw the studs back into the shaft and frame. Keep your shim stacks together for an alignment starting point. Get the MOOG parts/arms.
Having never done a lick of front-end work, I suspect that what you've stated here will make sense once I dig-in to the job myself. Bought the Moog upper and lower arms for the driver's side. We'll see how it goes.


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post #7 of 18 (permalink) Old 03-20-2017, 12:34 PM
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Once you have successfully completed the driver's side, you should do the passenger's side as well. I will save you from doing it in 6-8 months and paying for another alignment.


You need to get the spring compressor from Autozone or similar on their loan a tool program. Beware of O'Rilleys, they have a 2 day return policy, or you have bought it.


Compress the suspension (jack the wheel up) before tightening the compressor...it will be a lot easier. The spring does not like to clear the opening in the frame when the arm is in the lowered position, and it will not seat properly at the top. You can also turn the spring to get it aligned properly with the holes on the lower arm.

1991 OCC 461 (.030 over 454) BBC, 3.23 posi, flash to pass, drop spindles & springs, custom fender skirts, Impala rims, Recaros, Blazer console, MOMO/wood SW w/QR, custom wood shift knob, Pioneer DEH P77DH
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post #8 of 18 (permalink) Old 03-20-2017, 12:38 PM
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Another common culprit is broken sway bar link(s). They may not appear to be damaged,except for not actually being connected to anything anymore...
Not a bad idea to replace every couple years anyway. They don't cost much...

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post #9 of 18 (permalink) Old 03-20-2017, 03:57 PM
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Quote:
Originally Posted by atlantadan View Post
Bought the Moog upper and lower arms for the driver's side. We'll see how it goes.
IMHO I would do both sides at the same time

You may also need new spring isolators as yours may be dry, cracked or torn

all the suspension stuff wears out. As noted sway bar end links do also. I got the HD ones from NAPA

besides a BFH, a "pickel fork" is a tool used to separate tie rod, center link ends, etc. A cheap Harbor Freight one will work...or use a BFH alone but beating the crap out of stuff can have collateral damage

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post #10 of 18 (permalink) Old 03-20-2017, 04:09 PM
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In addition to what BALLS wrote, I learned this trick from a buddy of mine. He removed the cotter pin thru the castle nut, and then backed off the ball joint nut a couple times.

Then having the assembly under spring pressure, take a BFH and hit the inner end of the spindle, where the BJ nut passes thru. This will typically pop them apart, saving you the pickle fork maneuver in case you don't own one.

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